Food emulsions, for example sausage-type foods and various cheeses, are packaged by pumping them under pressure into casings of various sizes and codes. One form of casing that is used to package such food emulsions, e.g. meat emulsions or cheese emulsions, is a shirred casing made of material which may or may not be edible. The casing is formed into a tubular section which may be, for example, one hundred feet or more in un-shirred length. This relatively long length of casing is shirred into what is known in the industry as a shirred stick. The shirred stick may be of a length, for example, in a range of about 10 inches to about 18 inches. In conventional practice, the shirred stick is delivered to the food processor who typically will use it, for example, by sliding it over the elongated tubular horn of a food emulsion pump. The pump is then turned on and the food emulsion is forced through the horn. As the emulsion exits the horn, it enters the casing. The encased, packed food emulsion runs out continuously until the end of the casing material is reached, specifically, until the end of the shirred stick is reached. Thus, the casing is de-shirred as the food emulsion is extruded into it.
The casing material is relatively thin, in many cases being in the range of, for example, 0.0007 to 0.001 inches in wall thickness. The casing material may or may not be edible, for example, an edible casing being formed of collagen. The initiation of the process of stuffing the food emulsion into the casing or filling the casing, requires that the casing end be closed such that the pressure of the food emulsion will not just simply push through but instead will engage the end of the casing, thus pulling it and the balance of the casing alongwith the food emulsion as the food emulsion is extruded into the casing.
In the past, the emulsion stuffing machine operator, when changing casing sticks, would tie off, or in some other manner close, the end of the casing which was to first come into contact with the food emulsion. Or the operator could simply hold the end closed until sufficient food emulsion had been extruded into the casing to the point that extrusion would continue to de-shirr the casing off of the extrusion horn rather than push the food emulsion through the now-unheld end of the casing. In more recent times, it has been recognized that it is much more facile, reliable and economical if the shirred casing sticks are delivered from the manufacturer to the food processor with end enclosures already in place. Thus, the shirred casing stick with the enclosure in place can merely be slipped over the extrusion horn without concern for the tying-off, clamping, crimping or otherwise forming of an end-closure on the casing, tasks which formerly had to be undertaken by the food emulsion machine operator. The preference for shirred casing sticks with preformed end-closures has increased in direct relationship to the progressive development of food emulsion extrusion equipment; that development has progressed from the single extrusion horn machine to machines which have multiple extrusion horns and then to machines which are further automated such that a multiplicity of shirred casing sticks is loaded into the machine hopper with each of those sticks being automatically loaded onto the one or more horns of the extrusion machine. Furthermore, there have been additional developments of automated food emulsion stuffing equipment which have produced equipment and processes which do not use horns, but rather use other means for introducing the emulsion into the shirred casing sticks. Many of these recent developments of machines are extremely high speed, being capable of stuffing a shirred casing which, for example, on extension is 100 feet in length, in as short a period as 5 to 7 seconds.
In many of the food emulsion stuffing operations, the food emulsion is required to start up and stop every time extrusion is initiated into a new shirred casing stick and, respectively, when that casing stick has been expended and a succeeding new shirred casing stick is required. Because of such start up and stopping, the flow velocity and density of the initial portion of food emulsion, which, on start-up, is stuffed into the casing, is not always consistent with the balance of the rest of the encased emulsion. Thus, in many operations, this first portion is separated from the balance of the stuffed food emulsion, that first portion being recycled Because of this, in contemplating methods for closing the ends of food emulsion stuffing casings, consideration must be given to means of undoing or opening the end-closure to enable the easy extraction of this initial portion of food emulsion which then is recycled.
In other types of food emulsion stuffing operations, especially the automated processes used at present, and also those which are still considered manual but which entail multiple stuffing horns on a single food emulsion stuffing machine, it is possible to stuff casings with food emulsion such that even the initial end of the casing, with the first portion of food emulsion therein, is of sufficient density, consistency and size to be utilized. Thus in considering end-closures it is necessary to also incorporate the concept of end-closure permanency, in comparison to, for example, the hand held type of end-closure mentioned previously. Beyond this, consideration must be given to the strength of the end-closure itself. It must be sufficiently strong that the force and pressure of the food emulsion being extruded into it does not push out the end-closure. Another consideration in regard to end-closures for food emulsion casings is that some mechanism must be incorporated to release air which is trapped in the end as the food emulsion is extruded under pressure into the casing. Thus, it is considered an advantageous feature when end-closures can be formed which permit the escape of entrapped gases, but without the escape of any of the food emulsion.
The amount of casing material necessary to form an end-closure can be significant not only for cost reasons, regarding the amount of casing necessary to be used, but also in regard to the danger of excess casing material being trapped or entangled in braking or sizing equipment normally used to regulate the size, density and consistency of the food emulsion product. Excess casing material could be entrapped in the braking device, for example, to the extent that the pressure of the food emulsion being stuffed into the casing causes the casing to blow out, thus spewing food emulsion into the work area necessitating costly clean up, stoppage of the equipment and waste of the food emulsion product. Thus, some would consider the ideal casing to be that which uses the least amount of casing material as possible, in the formation of the end-closure.
Many different types and forms of end-closures have been tried in respect to the casings for food emulsion products. Examples for such end-closures are found in U.S. Pat. Nos. 3,162,833; 3,274,005; 3,865,954; 3,882,252; 3,892,869; 3,942,568; 3,942,569; 4,075,398; 4,411,048; 4,428,402; 4,525,984; 4,693,280 and 4,792,047. One type of end-closure shown, for example, in U.S. Pat. No. 3,162,893 simply twists the end of a de-shirred portion of the casing. Another example of this type of end-closure is shown in U.S. Pat. No. 4,792,047.
Another type of end-closure is simply made, principally, from inverting an end of the casing material and reinserting that inverted end back into the shirred portion of the casing stick, where it is compacted by one mechanism or another. U.S. Pat. No. 3,892,869 shows, perhaps, the simplest form of this where a straight linear compaction of the inverted casing portion is shown. U.S. Pat. No. 3,942,569 shows an end-closure which is formed by pulling out a section of shirred casing material, turning it sideways such that its axis is transverse to the longitudinal axis of the shirred casing material, and then pushing that turned portion, folding it back upon itself inside of the bore of the shirred casing stick. U.S. Pat. No. 4,075,938 shows an end-closure where casing material is de-shirred from the stick inverted and pushed back inside of the bore of the stick where it is more or less re-shirred.
Other types of end-closures are shown which don't clearly fit either of the above two categories. U.S. Pat. No. 3,274,005 shows a system wherein a hook is inserted axially through the full length of the bore of the shirred stick. The hook is then canted away from the line of the axis to catch an edge of the fore-end of the shirred casing stick. The hook is then centered along the stick axis with the caught end engaged by the tip of the hook. The hook is then twisted, wrapping the casing around its shank, and the hook, with the casing wrapped around it, is pulled axially back internally into the bore of the casing stick. The hook is then manipulated to free it from the entangled, wrapped portion of casing. Another embodiment of this invention shows a square ended shaft being utilized in place of the hook. It is necessary for the operator to engage a de-shirred portion of the shirred casing stick with this square end, while the square end is rotated, to form a twist. The twist is then pulled by the shaft back into the bore of the shirred casing stick where the square end shaft is disengaged.
U.S. Pat. No. 3,865,954 shows an end-closure which has a portion of the lead end of the casing stick de-shirred from it and inverted back into the bore of the stick. The inverted section of casing is then twisted to make a closure. U.S. Pat. No. 3,882,252 shows an end-closure which is formed by a pair of pinchers pinching the lead end of a shirred casing stick, de-shirring it, clamping the ends flatly together and either inserting glue to hold those ends closed or placing some form of tape around the compressed ends to hold them together, thus forming a closure. U.S. Pat. No. 4,411,048 shows an end-closure formed by a fluted tool which is first canted to engage the lead end of a shirred casing stick, then twisted to wrap the casing around that fluted end as the axis of the tool is brought back into alignment with the axis of the shirred casing stick. The tool with the casing twisted around it is then inserted into the bore of the lead end of the shirred casing stick where it is disengaged by opposite rotation of the fluted tool from the twisted end, and the tool is then withdrawn. An anvil is then brought into place, where the fluted tool had been, to act as a backstop while a compressor means is inserted from the opposite end of the shirred casing stick, through the full bore thereof, to compress the twist together. U.S. Pat. No. 4,428,402 shows an end-closure which is formed from de-shirring a substantial amount of casing from the shirred stick, twisting it into a closure about the mid-point of the de-shirred portion and then sleeving the portion, extending from the twist to the fore-end of the casing, back over the twist while inserting the now double-walled portion, back inside of the bore of the shirred casing stick. In one embodiment a gas escape aperture is provided in this end-closure.
U.S. Pat. No. 4,693,280 shows an end-closure which is formed in a manner generally the same as that shown in U.S. Pat. No. 3,865,954 wherein a section of the fore-end of a shirred casing stick is de-shirred and pushed back inside of the bore of the shirred casing stick, being partially inverted. This partially inverted section is then compressed in a manner similar to the compression described above in regard to U.S. Pat. No. 4,411,048.
Many of the end-closures described above which are used to close off the end of casings suffer from various concerns which make them less than ideal. For example, many of the foregoing prior art end-closures use substantial quantities of shirred casing. Primary examples of this are U.S. Pat. Nos. 3,942,568; 3,942,569 and 4,693,280. Some of the above referenced end closures require the extension of tools through the full length of the casing stick, from the opposite end of that stick, thus increasing the potential for damage to the casing in the formation of the end closure. Examples of this are U.S. Pat. No. 3,274,005 and 4,411,048.
It is deemed quite important in the manufacture of food emulsion products to eliminate as much as possible all potential for inclusion of foreign materials or articles in the food emulsion. Thus, particularly in the use of automated packaging equipment for linked material, there is a great degree of apprehension in regard to using any type of end-closure which would introduce such foreign material or articles. U.S. Pat. No. 3,882,252 creates an end-closure which has such type of foreign material or articles introduced and therefore suffers from this deficiency. In the food emulsion packing industry, there is great concern for any type of end-closure which forms a double wall on the casing which could potentially be subject to entrapment in the sizing or braking device used if pushed out of the shirred casing stick by the initial impact of the extruding food emulsion on the end-closure. Examples of the prior art which encounter this as a problem include U.S. Pat. No. 4,428,402 and 4,693,280.
Thus, there is a need for an end-closure design, and a method for forming that end-closure, which avoids the usage of all but a very small portion of the fore-end of the casing stick and which can be readily unwrapped in the event that the initial portion of the food emulsion is not up to standard and, thus, must be stripped for recycling, but also an end-closure which is sufficiently strong and permanent enough that it can be utilized when the initial portion of the food emulsion stuffed into the casing meets the requirements of the specification for use. Also to be included should be a means for egress of otherwise entrapped gases, such as, for example, air in the casing. Also included should be means to cushion the initial shock of the food emulsion as it impacts the casing closure to overcome static inertia and friction to get the casing moving and to avoid the end-closure being pushed out by the initial impact of the extruding food emulsion on that end-closure. And finally, what is necessary is a means of formation of such an end-closure which does not require an insertion of any tooling through the full length of the bore of the shirred casing stick, confining the manipulation of the casing material and the contact with the tooling to only the foremost end of the casing. Such an end-closure, of course, needs to be free of foreign materials or articles and should be adaptable to various casing sizes.